System and method for printing motion picture films



June 1934- D. A. WHITSON ET AL 1,963,342

SYSTEM-AND METHOD FOR PRINTING MOTION PICTURE FILMS Filed Oct. 10, 19272 Sheets-Sheet l I M Q):

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SYSTEM AND METHOD FOR PRINTING MOTION PICTURE FILMS Filed Oct. 10, 19272 Sheets-Sheet 2 ATTOAZA/E) D. A. WHITSON r AL 1,963,342

- Patented June 19, 1934 UNITED STATES PATENT OFFICE SYSTEM AND METHODFOR ram'rmo MOTION morons: FILMS Application October 10, 1927, SerialNo. 225,365

1 Claim.

This invention relates to motion picture films, and especially to themanufacture of film positives that are used for projection purposes.

In order to obtain a clear idea of the purposes and objectsof ourinvention, it is desirable to point out briefly the methods in use todayin the various steps of producing a satisfactory film for projectionpurposes. In the first place, the cameraman, operating a camera, securesexposures of a series of scenes, on negative films. These are developed,and from them can be printed the desired number of positive films whichare used for projection purposes.

Now let us consider the problems the cameraman must solve. The sceneschange rapidly; from indoors to' outdoors, from close-ups to long shots;and each scene thus has a light value that is diflferent from theothers. The cameraman in order to secure a good negative, attempts tocompensate for these varying light values by ad justing the opening ofthe lens in the camera;

but it has been found in practice that the negative thus produced stillhas undesired departures from the desired degree of translueency.Contributing factors may be the inherent and unavoidable variations incranking speed; or errors in developing.

At any rate, it is well-known that usually if such a negative having aplurality of scenes is printed uniformly (that is, all scenes on thenegative subjected to the same intensity and duration of illuminationduring the process of printing), then at least some of the scenes willbe--,

found to be of an inartistic nature; and this is apt to occur even ifthe negative film exposures are substantially correct. The practiceaccordingly has been to print the negative non-uniformly; that is, somescenes on the negative may be subjected to a greater duration ofprinting, or illumination during printing, than other scenes. The extentof this variation in printing intensity is usually merely a matter ofguesswork and of personal judgment. Since such judgment is grounded ontrail human nature, it is not at all surprising that some scenes must beprinted over several times before the desired pictorial effect isproduced. This item alone, involves the loss of huge sums, for not onlyare the films wasted, but the time and operating expense involved inproducing these discarded films.

In the judgment required to determine the time of printing or theintensity of the illumination during printing, the attempt is made toobtain a desired artistic illumination on the screen when the film isprojected. This involves a decision about the desired light transmittingproperties of the printed positive film; and this must be translatedinto terms of printing time and printing illumination when the negativeis printed. In the iollowing description and in the claim, the termtranslueency will be used to designate these light transmittingproperties, both for the negative and for the print; and in this way, aconcise expression can be used instead of the unwieldy one that isperhaps more accurate.

With the aid of our invention, it is possible to determine the intensityof printing precisely and rapidly without the introduction of the humanelement. The term .intensity of printing is intended to mean theduration of printing, or the intensity of illumination used forprinting, or the combination thereof. Since great quantities of filmfootage are printed every year in the motion picture industry, theconsequent saving in expensev due to the use of our method is verylarge.

In most scenes, the interest is usually localized at a definite place ofthe "frame (this term referring to a single unit picture); ordinarily,it is about at the center of the picture, but .occasionally it maydeviate from this position, such as when the main character orcharacters move about. The artistic sense or feel is best satisfled whenthis focus of interest is desirably or artistically illuminated on thescreen; that is, when the translueency of that portion of the frame iscorrect; and it is more or less a matter of indifference whether therest of the frame is as correctly illuminated. It is another object oiour invention to make it possible to secure this artistic or desirableeffect as regards the center of interest (irrespective of its positionin the frame), in a precise and simple manner, and without the necessityof the exercise of trail human jud ment.

Our invention possesses many other advantages, and has other objectswhich may be made more easily apparent from a consideration of oneembodiment of our invention. For this purpose we have shown a form inthe drawings accompanying and forming part of the present specification.We shall now proceed to describe this form in detail, which illustratesthe general principles of our invention; but it is to be understood thatthis detailed description is not to be taken in a limiting sense, sincethe scope of our invention is best defined by the appended claim.

Referring to the drawings:

Figure 1 is a diagram showing a system by the aid of which our inventioncan be practised;

2 deta grain of a section of a negative and the means whereby the centerof interest of the frame can be used to determine the printingintensity; and

Figs. 3 and are general front and side views of one form apparatus thatis used for practicthe invei The system 1. clves in general th provisionor a device that responds to the translucency of negative, or least,selected portions of the negative. The translucency of any such portioncan then be compared with a definite desired standard in a manner to helater described; and the quantities cor ponding to these relativetranslucencies can be utilized to determine the printing intensity. Fornroviding a uniformly good print, each scene 1e negative should besubjected to s measuring process at least at one or two frames includedin the scene. The term scene is used herehi in the usual technicalsense; that a series of frames or individual pictures in which theexposures were produced in rapid succession, and usually implies thatthe same scenery is used for all such frames.

Thus in we show a pair of reel mechanisrns and l which merely form aconvenient means ror passing th negative 13 across a table or supportwhereby the translucency of parts of the can be determined by apparatuslocated adjacent the table. Guide rollers 15, M

can he provided desired to maintain. the 5.11.1 is in .0 .l

proper relation. the table.

In order to provide an indication the "e" tive translucency or anyportion of film t is a source of light 17 which is arranged to directlight against him 23, and the light transmitted thereby serves toactuate a light responsive device to he later described. The light 1!can cor venientiy he an electric light, supplied with 815.1- rent froman electric circuit including a source, such as battery Since foraccuracy it is de" sirable to have as miforzn light as possible, thecurrent supplied by source 1 is arranged to be accurately regulated by avariable resistance 19; the voltmeter 20 is provided and is connectedacross lamp 1? to furnish a check upon the lamp energization. Furthrmore, special care should he taken to ensure good contact betwe n thelamp 1'? and its socket.

Preferably there is provided a curved reflector such as 21 for focusingthe light upon an arrangenient whereby the rays stay parallel theilhimination is uniform; such as a condenser lens 22. The table hasaperture 23 therein permitting the passage of the light through nun Thelight is then caused to afifect a device that translates light energyinto a readily measurable energy, such as electricity; for example, thelight can be trained as converging lens 24- onto photoelectric cell 25.

A photoelectric cell such as 25 usually has a pair of spaced electrodeslocated in an appropriate transparent container, and having such aproperty that there is an electronic emission from one, such as thecathode 26, to the other such as the anode 27, whiclrvaries with theamount or" illumination to which said cathode is subjected. Suchcathodes are now well known, and usually consist of a metal plate coatedwith a compound or amalgam of the alkali metal group. These electrodescan be connected to an external circuit, in which there is included asource of potential such as battery 28. This battery has its negativeterminal connected to cathode 26; and

Vii. v;

its voltage is as in "ii/hen there is variation in illunil' ion, thereis a correspondin variation in electronic emission electrode andconsequently there is a variation in the cu ent fro 2 external circuitconnecting e electro es. current responsive device so." l as agalvanoineter 29 can be included in the circuit to provide a1. -m. therelative illumination values. This in is preferably inicroammetcr, s ceth variations of course small.

variable shunt l. fiat 15121.1

the lig t responsive device possible ea"-" he manner of use ou nvebemore carefully detailed. -iere'nce with which the film ti nsluc becompared, initially the syster passing light fro lamp th' which has a stcard t'anslucen desired to maintain in the course negative is not atthis ta'cle the light encounteri; o of; screen ill. The resistance ljusted so as to maintain lain ndard value whic". is to be 1"tnieasureinents. LlkBWlSc device 25 cl by The light pas Jedance of cellfrom cathode ates a passage carefully inanipulat medial value on barbitrarily assigned a nuin' dicating the standard or desired cency ofNow screen as AS moved o handle 32, negative sses eve 14;. Two or threeframes of eacl' over aperture for a period nut the apparatus to 1 no itis often desirable to measu lucency of only a portion of the center ofinterest of frame. The relative position of the iris and frame undertest is diagrammatically illustrated in Fig. 2. ihis iris being spacedsome distance lad above film 13, has the effect of gradually shading offthe light around the edges of the illuminated portions of th frame undertest; this is desirable from an artistic standpoint. It is of coursepossible to secure the same effect by grading the iris density. Irisesthat have increasing densities as the edge of the opening is approachedare well-known, and can be utilized for this purpose. For example, theiris opening, instead of being a smooth circle, can be star-shaped orcan have other variant forms, forming more resistance to the passage oflightadjacent the edges. The same effect can also be obtained by placingthe iris at such a point in the optical system as to serve partly as adiffuser of light. When an iris is thus used, the apparatus must bereadjusted to agree with the amount of light that can pass through theiris.

As before stated, two or three scattered frames g 'of each scene can besubjected to the operation of the apparatus, a record being kept foreach scene. The translucency of the frame under test determines thequantity of current flowing between electrodes 26 and 27. If thistranslucency is greater than that of the standard screen 31, themicroammeter 29 will be deflected further than the index 8, and a recordis kept of this for the scene under test. On the other hand, if thetranslucency is below that of screen 31, the pointer of microammeter 29will indicate some figure diflerent from 8. For convenience in indexingor recording, it is advisable that for translucencies less thanstandard, the reading be larger, to indicate the necessity for greaterintensity of printing; and conversely, for translucencies greater thanstandard the reading should be less. Thus galvanometer 29 will have aninverse reading scale, the larger numbers corresponding to a smallerdeflection. Periodically it is advisable to try screen 31 and to notewhether the instrument 29 will indicate the desired standard value, forsuch influences as temperature or the like may cause undesired, even ifminute, changes in the readings.

The numbers noted for the scenes as thus described are associated withprinting intensities in an inverse manner. Thus the higher thetranslucency, the lower should the printing intensity be. The exactcalibration between relative translucence as thus determined andprinting intensity can be empirically determined and tabulated orplotted. Thus no guesswork or human judgment is needed for the printingof negatives.

While the apparatus is not in use, it can be easily rendered inactive bythe opening of switches 34 and 35, in the lamp circuit and in themeasuring circuit respectively.

In Figs. 3 and 4 one practical embodiment of the device is illustrated.A convenient stand or support 36 can be used, upon which the table 14 islocated. Beneath the table is a compartment 37 for the photoelectriccell 25; and on each side thereof there are the reels 11 and 12. Thegalvanometer or microammeter 29 can be conveniently mounted on the frontof a sloping panel 38, as well as any other instruments such as 20 and31 that may be desired. The lamp structure 21, 22 can be convenientlysupported over table 14 as by a horizontal arm 39. The switches 40 forcontrolling the various circuits can also be conveniently mounted ontable 14. If desired, a footage counter 41 and scene counter 42 of anydesired form can also be provided.

It is, however, evident that the basic ideas of our invention are in nowise dependent upon any particular mechanical arrangement, the formillustrated being merely one that has been tried out successfully. mentscan readily be provided.

We claim:

The method of producing a motion picture print from a negative that hasscenes therein in which the translucencies deviate from one another andfrom a desired translucency, which comprises transmitting light of fixedeffective standard intensity through a portion only of at least oneframe in each scene, said portion being centralized at the center ofinterest of the picture in the frame, obtaining an indication of therelative translucencies of said portions, and printing said scenes withan intensity determined by said relative translucencies.

' DELMAR A. WHITSON. LEWIS W. PHYSIOC.

Other mechanical arrange-

